![]() ![]() And - like any good scientist - Eratosthenes did the experiment. Sure, the Sun came closer to being directly overhead at Noon on the Summer Solstice in Alexandria than at any other time during the year, but vertical objects still cast shadows. Daniel Ramirez of flickr, under a c.c.a.-by-s.a.-2.0 license.īut Eratosthenes knew that this wasn’t the case where he was, in Alexandria. Lahaina Noon in Hawaii, where objects cast completely vertical shadows twice a year. As you can see, below there are indeed places in there world where this is the case. And if you had a completely vertical object, it would cast absolutely no shadow. In other words, the Sun would be directly overhead at this time, not a single degree to the South, North, East or West. The shadow of someone looking down a deep well would block the reflection of the Sun at noon. In particular, it said that, on the Summer Solstice, Believe it or not, this was the situation that Eratosthenes of Cyrene found himself in, some 2300 years ago, when he became the first person to not only conclude that the Earth was round, but to measure its physical size! While living in Alexandria, Eratosthenes received some amazing correspondence from the city of Syene in southern Egypt. Perhaps you don't want to know about heliocentrism, about the existence of the Moon or even a knowledge of basic geography beyond the tiny region where you live. Image credit: Windows to the Universe Original (Randy Russell), under a c.c.a.-s.a.-3.0 unported license.īut perhaps you don't even want 1500s level technology to rely on. The two ways Earth could cast a circular shadow on the Moon: by being a spherical object (bottom) or.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |